Humidifying apparatus



April 22, 1941.

w. w. CUMMINGS, JR

HUMIDIFYING APPARATUS Filed Jan. 11, 1940 In (2612 for.

m eamq Patented Apr. 22,1941

. UNITED STATES PATENT OFFICE HUMIDIFYING APPARATUS William WarrenCummings, Jr., Marshfleld, Mass. Application January 11, 1940, SerialNo. 313,387 7 Claims. (01. 261-15) This invention relates to a novelapparatus for humidifying dry air in an enclosed space.

- It is the primary aim and object of the present invention to devise anapparatus for humidifying dry air in an enclosed space without requiringthe elaborate and expensive duct systems and the. large volumes of aircirculation which are so essential in the conventional humidifiers toprevent condensation of the added water vapor in the air and secure itsdistribution.

- It is also among the objects of the present invention to provide ahumidifying apparatus which is readily assembled into a self-containedunit of relatively small dimensions and lends itself to readyinstallation at'most anyplace,

Before explaining in detail the present invention it is to be understoodthat the invention is not limited in its application to the details ofconstruction and arrangement of parts illustrated in the accompanyingdrawing, since the invention is capable of other embodiments and ofbeing practiced or carried out in various ways.

Also it is to, be understood that the phraseology or terminologyemployed herein is for the purpose of description and not of limitation,and it is not intended to limit the invention claimed herein beyond therequirements of the prior art.

In the drawing the figure is a longitudinal section through a humidifierwhich embodies the present invention.

A In the drawing, the reference numeral l designates a suitablyconstructed container which is closed except for an air inlet l2 and anair outlet l4. The container is preferably placed in the enclosed spacewhose air is to be humidified. Suitably mounted in the container at theinlet l2 thereof'is a conventional shell and tube type heat exchanger 16through which air must pass in order to enter the container in themanner indicated by the arrows I8. Also provided in the container l0 bytransverse partitions 20, 22 is a reservoir 24 which contains water.Water from any suitable source is admitted to the reservoir 24 through avalve 26, having a conventional airfilled float 28 for controlling thevalve so that the water level remains substantially constant. A suitablepump 30, driven by an electric motor 32, has its intake side inpermanent communication with the water supply in the reservoir through aconduit 34, while its discharge side communicates through a conduit 36with the intake end of any suitable heater coil '38 in a shell 40 whosebottom end is open to admit the heat from a gas burner 42 and whose topend communicates with a flue (not shown) for the escape of the productsof combustion. The gas which. ignites the burner when gas from anysuitable source is admitted through a conduit 44. To this end, anormally closed gas valve 46 in the conduit 44 is opened when a solenoid48 is energized. The discharge end of the heater coil 3! communicatesthrough a conduit 50 with the water-intake end of the heat exchanger itthrough which water flows counter to and sepa rated from the flowing airtherein and in heatexchange relation with the latter. The waterdischarge end of the heat exchanger 66 is connected through a conduit 52with a spray nozzle 54 which is adapted to spray hot water through theflowing heated air in the container andinto the reservoir 26. Suitabletransverse baffles 565 and 58in the container cause the heated air toflow counter to water spray from the nozzle "at as indicated by thearrows 59. A horizontal partition 60 in the container together with thepreviously mentioned partition 22 therein forninot only a separatechamber 62, in which the motor driven pump 30 and the water heater 3&3,til and 42 are housed, but also an air duct (it from the inlet l2 to thereservoir 26. Provided on the earlier mentioned bafiie 5t and partition22 and on an intermediate partition t6 are eliminator plates 68 pastwhich'the heated and sprayed air fiows in the manner indicated by thearrows iii. These eliminator plates remove any moisture in suspensionfrom the air stream. Suitably mounted in the container it as on thepedestal it, for instance, is a motor-driven ian t i whose discharge endcommunicates with the outlet it. The fan 14. when operating, draws airinto the container through the inlet i2 and causes it to flow therein inthe manner indicated by the arrows I8, 59 and I0 before being expelledthrough the outlet it.

L represents line wires from which branch leads l6 and '18 that completethe circuit for the pump motor 32 ii a switch in the lead It is closed.This switch 80 is so operatively associated with a humidostat H in thespace whose air is to be humidified that said humidostat closes theswitch when the humidity in said space is below a predetermined minimum,and opens said switch when the humidity is above said minimum. Parallelwith the pump motor circuit is the energizing circuit for the gas valvesolenoid 48 which consists of leads 82 and 84 that branch oil the leadsI6 and I8, and any suitable limit switch 86 which is normally closed andis opened in response to a predetermined high water temthe circuit forthe pump motor 32 may be closed by the action of the humidostat H, theenergizing circuit for the gas-valve solenoid ll will be opened as soonas the water temperature in the conduit II reaches said predeterminedhigh value at which the limit switch 88 will be opened. Also branchingof! the leads I. and 18 are two leads 88 and Oil which complete aparallel circuit for the fan motor when any suitable thermostatic switch82 in the lead 88 is closed. This happens when the temperature of theheated and sprayed air is sufllciently high to close the thermostaticswitch 88.

In operation, the pump 3| starts to operate when the humidostat H closesthe switch ll, with the result that water from the reservoir 24 isforced through the heater coil and the heat exchanger l6 from where itpasses to the spray nozzle 54 and thence back into the reservoir, withthe exception of whatever moisture has been absorbed by the aircontacted by the water spray. The closing of the pump motor circuitresults in immediate closing of the parallel cir- 'cuit for the gasvalvesolenoid II, with the result that gas is admitted to the burner 42and the gas is ignited by the automatic pilot. The temperature of thewater flowing through the exchanger l6 and the spray nozzle 54 is thusraised until the water temperature in the conduit 5| becomessufilciently high to cause opening of the limit switch as. When thistakes place, the burner 42 becomes extinguished until the watertemperature in the conduit 50 drops sumcienltly to cause re-closing ofthe limit switch It. The fan will not operate until the temperature ofthe sprayed air is sufiiciently high to close the thermostatic switch92, thus avoiding the discharge of air whose temperature is so low thatthe water vapor carried thereby would condense at the temperature in thespace. Actual tests have shown that diflerent moisture contents incontacting air masses will almost instantaneously have a common vaporpressure. Thus, where in a small part of a room a high temperature and ahigh relative humidity at a high vapor pressure is maintained and therest of the room is at a lower temperature and a lower relative humidityat a lower vapor pressure, the moisture contained in the air in saidsmall part of the room will flow, without necessitating any air motion,to the air in the rest of the room, i. e., to the lower vapor pressure.This phenomenon is used with great advantage in the present humidiiyingapparatus, and the end iought is to obtain in the air which is expelledfrom the container 9. very high vapor pressure. In order to accomplishthis, the air expelled from the container must have the high temperatureat which such a high vapor pressure is possible. As the vaporization ofthe added moisture will entail heat losses, heat has tobe furnished inexcess of that requii ed to bring the air which is to carry the addedmoisture to said high temperature. The spray water as well as theflowing air in the ontainer are accordingly heated by the water water38, 42 and by the heat-exchange between be heated water and the indrawnair in the xchanger 16. Furthermore, the relative humidty of theexpelled air must be sufliciently low to revent condensation of thewater vapor therein iefore vapor transfer has taken place.

As a practical example, a heated room has been maintained at atemperature of 80 F. and per cent relative humidity (.44 inch oi mercury.perature in the conduit 5i. Thus, even though vapor pressure) byheating the spray water in the heater coil 38 to approximately 180 F.,while the indrawn air was heated in the exchanser It and bythe waterspray from the nozzle 54 to an approximate temperature of 150 F. Due tothe heat losses on account of the evaporization oi the moisture, thetemperature of the air expelled from the container had dropped toapproximately 104 F. and its relative humidity was around per cent,corresponding to a watervapor pressure of 1.4 inches of mercury. Hencethe vapor pressure differential at the outlet of the container and therest of the room was 1.4-.-i4=.96 inch of mercury column, with theresult that the vapor flowed immediately from the higher pressure to thelower pressure.

With the present method of moisture injection, only a very small amountof .air circulation is necessary, and that only within the container ofthe humidifier unit. Previously essential, expensive and bulky duct workfor the equal distribution of the moisture about the space to behumidified is unnecessary and entirely eliminated, and condensationaround the unit cannot take place at the high temperature maintained inthe expelled air. Larger amounts of moisture may be injected fasterthan-with the customary humidifiers and at less cost as well as withless equipment. The humidifier itself is much smaller than present-dayequipment for the same capacity, and the various controllers assureproper operation of the apparatus at all times.

While in the present instance gas is used for heating the water in thecoil 38 and the indrawn air is heated by the heat-exchange between saidheated water and air, it is fully within the scope of the presentinvention to use oil heat or steam in order to heat the water in saidcoil or the indrawn air in the exchanger It, or both. Thus, if steam isused, the shell 40 serves preferably as a steam jacket to which steamfrom any suitable source is permanently admitted. This eliminates thelimit switch 8 and the solenoid-operated gas valve 46, and the water inthe coil 38 is then always sumciently hot so that the thermostaticswitch 92 in the fan-motor circuit may also be dispensed with. The thusheated water in the coil 38 may first flow through the heat exchanger ISin heat-exchanger-relation with the air fiowing .therethrough beforebeing conducted to the spray nozzle 54, or said water may directly flowto said spray nozzle without first flowing through the heat exchanger,In the latter case steam from the same source is directly conductedthrough the heat exchanger IS in heat exchange relation with the indrawnair therein.

I claim: I l

1. A humidifier for a space comprising a container having an inlet andan outlet, first means for drawing air from said space into thecontainer through said inlet and expelling it into said space throughsaid outlet, means for heating the indrawing air, a water reservoir inthe container, a water heater, a gas burner therefor with an automaticpilot, a normally closed valve for admitting gas to said burner, asolenoid opening said valve on being energized, a spray nozzle in thecontainer in communication with said heater and adapted to spray hotwater through the flowing heated air into said reservoir, an electricpump for forcing water from the reservoir through said heater to saidnozzle, and parallel energizing circuits for said solenoid and pump,respectively, and including a common switch for simultaneously openingand closing said circuits.

2. A humidifier as set forth in claim 1, further including in theenergizing circuit for said solenoid only a thermostatic switch which isopened when the temperature of the heated water is above a predeterminedmaximum temperature.

3. A humidifier as set forth in claim 1, in which said first meanscomprises an electric fan and an energizing circuit therefor including athermostatic switch in the path of the heated air between the spraynozzle and outlet for closing the latter circuit when the temperature ofsaid air is a-oove a predetermined minimum temperature.

4. A humidifier as set forth in claim 1, in which said first meanscomprise an electric fan and an energizing circuit therefor including athermostatic switch in the path of the heated air between the spraynozzle and outlet for closing the iatter circuit when the temperature ofsaid air is above a predetermined minimum temperature, and theenergizing circuit for the solenoid includes a thermostatic switch whichis opened when the .temperature of the heated water is above apredetermined maximum temperature.

5. A humidifier as set forth in claim 1, further comprising a humidostatin said space so operatively associated with said switch as to close thelatter every time the humidity in said space is below a predeterminedminimum.

6. A humidifier comprising a casing having an inlet and an outlet in itsfront and rear wall, respectively; a first partition in the casingdividing the same into two separate chambers and comprising a horizontalwall portion extending from said front wall below the inlet and acontinuing vertical wall portion extending to the bottom of the casingat a distance from said rear wall; a second transverse partition in thecasing between said vertical wall portion and rear wall and extendingfrom the bottom of the casing into close proximity to the top thereofand defining together with said vertical wall portion a water-holdingreservoir in the casing; two spaced transverse walls in the casingbetween and spaced from said vertical wall portion and second partitionand forming a spray chamber above the reservoir, the transverse wallnearest said vertical wall portion extending from the top of the easinginto close proximity to the water level in the reservoir and the othertransverse wall projecting helow said water level and extending upwardlyinto close proximity to the top of the casing; a heat exchanger mountedat said inlet; a water heater in the smaller chamber in communicationwith the intake end of said exchanger; a pump in said smaller chamberhaving its intake end in communication with the water in the reservoirand its discharge end in communication with said water heater: a spraynozzle in said spray chamber near the top of the casing andcommunicating with the discharge end of said exchanger; an eliminatorbetween said other wall and second partition; and a fan at said outlet.

'7. A humidifier as set forth in claim 6, in which said eliminatorcomprises a third transverse partition in the casing between said otherwall and second partition and extending from the top of the casing intoclose proximity to the water level in the reservoir, and eliminatorplates on those surfaces of said other wall and second and thirdpartition which face each other.

W. WARREN CUIVINIINGS, JR.

